fix eslint for opus

package.json

@@ -26,7 +26,6 @@
   },
   "homepage": "https://github.com/hydrabolt/discord.js#readme",
   "dependencies": {
-    "node-opus": "^0.1.13",
     "object.values": "^1.0.3",
     "superagent": "^1.5.0",
     "tweetnacl": "^0.14.3",
@@ -36,6 +35,9 @@
     "fs-extra": "^0.30.0",
     "jsdoc-parse": "^1.2.7"
   },
+  "optionalDependencies": {
+    "node-opus": "^0.1.13"
+  },
   "engines": {
     "node": ">=0.12.7"
   },

src/client/voice/opus/NodeOpusEngine.js

@@ -6,6 +6,7 @@ class NodeOpusEngine extends OpusEngine {
   constructor(player) {
     super(player);
     try {
+      // eslint-disable-next-line import/no-unresolved
       opus = require('node-opus');
     } catch (err) {
       throw err;